1. Field of the Invention
This invention relates to a manufacturing method for forming an elongate body having a thickness change, and in particular, to a manufacturing method for forming an elongate body used in a window molding for automobiles that has vertical members molded into a section different from that of a horizontal member.
2. Description of Related Art
A window molding for automobiles that is produced by a conventional manufacturing method for forming an elongate body having a thickness change is disclosed in FIG. 6 to FIG. 8.
As shown in FIG. 6, the window molding is molded into an elongate shape that is composed of a pair of vertical members 10 and a horizontal member 20. The vertical members 10 are respectively fitted into gaps between right and left edges of a front window glass 1 and a window frame 2 of an automobile windshield. The horizontal member 20 is fixed into a gap between an upper edge of the glass 1 and the frame 2.
As shown in FIG. 7, the vertical member 10 has a leg 11 inserted into the gap between both the lateral edges of the glass 1 and the frame 2. An inner support 12 and a retaining lip 13 are protruded from the leg 11. The inner support 12 sustains a rear surface of a perimeter of the window 1. The retaining lip 13 is elastically contacted with an inner surface of the frame 2. An outer support 14 is formed on the leg 11 so as to face the inner support 12 and touch a front surface of the window 1. The leg 11 is secured by an adhesive 5 to the frame 2 which is provided on both lateral sides of the automobile body. A head 15 is integrally formed on the leg 11 at a position remote from the outer support 14, so as to face support 14. A seal lip 16 is protruded from the head 15 toward the frame 2 and is elastically contacted with an outer surface of the frame 2. A folding piece 17, substantially of an inwardly bending angle section, is integrally formed between leading ends of the outer support 14 and the head 15. A fixed, closed cavity 18 is defined by a space surrounded by an upper part of the leg 11, the head 15, the folding piece 17 and the outer support 14.
The horizontal member 20 is molded into a section shown in FIG. 8 by extruding a synthetic resin into the same shape as the vertical member 10, pressing the head 15 of the extruded vertical member 10 in its thickness direction by a press roller or the like, thereby obtaining a deformed head 21. The folding piece 17 is then bent inwardly so as to be folded into a deformed folding piece 22. A deformed cavity 23, having a smaller and different closed section as compared with cavity 18, is defined by a space surrounded by the upper part of the leg 11, the deformed head 21, the deformed folding piece 22 and the outer support 14. The remaining construction of the horizontal member 20 is same as the vertical member 10. As shown in FIGS. 7 and 8, a metal wire 6 is inserted in the molding for reinforcement, preventing its elongation. A dam 7 seals the adhesive 5 between the glass 1 and frame 2.
Next, a manufacturing method is described for forming the a conventional elongate body have a thickness change, as constructed above.
For molding the window molding, a synthetic resin such as a polyvinyl chloride is extruded by an extruder into the same shape as the vertical member 10. The head 15 of the extruded body corresponding to the horizontal head 20 is pressed by the press roller in the thickness direction, thereby bending inwardly the folding piece 17 at its corner and piling the deformed folding piece 22 and the deformed head 21 on the outer support 14. Then, the extruded body is cooled, solidified and cut to length to complete the window molding. When the window molding is fitted on the perimeter of the window glass 1, the heads 15 of the vertical members 10 project from the window 1. Thus, an outer surface of the folding piece 17 prevents rainwater swept by a wiper 3 from overflowing the frame 2 and guides and drains the rainwater downward along the lateral edges of the window 1. The horizontal head 20 protruded from the window 1 less than the vertical members 10, so as to improve aerodynamic characteristics.
In the conventional manufacturing method, since the horizontal head 20 is obtained by pressing the head 15 of the extruded vertical member 10, the outer support 14, the deformed folding piece 22 and the deformed head 21 of the horizontal member 20 have the same thicknesses respectively as the outer support 14, the folding piece 17 and the head 15 of the vertical member 10. Since the vertical member 10 has a thickness which gives it a predetermined rigidity in order to keep its shape after being fitted to the window 1, the overall thickness of the joined outer support 14, deformed folding piece 22 and head 21 is larger than necessary. As a result, the height the horizontal member 20 protrudes from the window 1 is increased, thereby, possibly affecting the aerodynamic characteristics.